Smooth Frictional Contact between Beams in 3D

In this paper a smoothing procedure for the 3D beam-to-beam contact is presented. A smooth segment is based on current position vectors of three nodes for two adjacent finite elements. The approximated fragment of a 3D curve modeling a beam axis spans between the centre points of these elements. The curve is described parametrically using three Hermite polynomials. The four boundary conditions used to determine the coefficients for each of these polynomials involve co-ordinates and slopes at the curve ends. The slopes are defined in terms of the element nodal co-ordinates, too, so there is no dependence on nodal rotations and this formulation can be embedded in a beam analysis using any type of beam finite element. This geometric representation of the curve is incorporated into the 3D beam-to-beam frictional contact model with the penalty method used to enforce contact constraints. The residual vector and the corresponding tangent stiffness matrix are determined for the normal part of contact and for the stick or slip state of friction. A numerical example is presented to show the performance of the suggested smoothing procedure in a case of large frictional sliding.

Key words: 3D curve smoothing, Hermite polynomials, frictional contact, consistent linearisation.